Add missing OP_POWER operator to Variant

[AThousandShips]

I don't think this breaks compatibility as there's no binary compatibility to maintain here, the mapping to the engine is done via the interface macros, but need verification here

• Fixes: Variant::Operation::OP_POWER is missing #1348

Edit: This likely fixes Variant::evaluate which tries to map Operator to GDExtensionVariantOperator which doesn't line up

[Naros]

Hi @AThousandShips I can confirm this will be okay in its current form and it does fix Varian::evaluate. I had to build a bridge enum locally to deal with this so it's nice to see this fixed so I can remove the bridge handler going forward.

[dsnopek]

Thanks!

Assuming I'm understanding this right, currently Variant::evaluate() is broken with all operators after OP_POWER because missing that item means the enum in godot-cpp doesn't line up with the enum in the GDExtension interface.

In any case, this change looks great to me :-)

[akien-mga]

Thanks!

[AThousandShips]

Thank you!

[limbonaut]

Yep, thanks!

[dsnopek]

Cherry-picking to 4.2 in #1372

[dsnopek]

Cherry-picking to 4.1 in #1373